.TH std::jmp_buf 3 "2024.06.10" "http://cppreference.com" "C++ Standard Libary"
.SH NAME
std::jmp_buf \- std::jmp_buf

.SH Synopsis
   Defined in header <csetjmp>
   typedef /* unspecified */ jmp_buf;

   The std::jmp_buf type is an array type suitable for storing information to restore a
   calling environment. The stored information is sufficient to restore execution at
   the correct block of the program and invocation of that block. The state of
   floating-point status flags, or open files, or any other data is not stored in an
   object of type std::jmp_buf.

.SH Example


// Run this code

 #include <array>
 #include <cmath>
 #include <csetjmp>
 #include <cstdlib>
 #include <format>
 #include <iostream>

 std::jmp_buf solver_error_handler;

 std::array<double, 2> solve_quadratic_equation(double a, double b, double c)
 {
     const double discriminant = b * b - 4.0 * a * c;
     if (discriminant < 0)
         std::longjmp(solver_error_handler, true); // Go to error handler

     const double delta = std::sqrt(discriminant) / (2.0 * a);
     const double argmin = -b / (2.0 * a);
     return {argmin - delta, argmin + delta};
 }

 void show_quadratic_equation_solution(double a, double b, double c)
 {
     std::cout << std::format("Solving {}x² + {}x + {} = 0...\\n", a, b, c);
     auto [x_0, x_1] = solve_quadratic_equation(a, b, c);
     std::cout << std::format("x₁ = {}, x₂ = {}\\n\\n", x_0, x_1);
 }

 int main()
 {
     if (setjmp(solver_error_handler))
     {
         // Error handler for solver
         std::cout << "No real solution\\n";
         return EXIT_FAILURE;
     }

     for (auto [a, b, c] : {std::array{1, -3, 2}, {2, -3, -2}, {1, 2, 3}})
         show_quadratic_equation_solution(a, b, c);

     return EXIT_SUCCESS;
 }

.SH Output:

 Solving 1x² + -3x + 2 = 0...
 x₁ = 1, x₂ = 2

 Solving 2x² + -3x + -2 = 0...
 x₁ = -0.5, x₂ = 2

 Solving 1x² + 2x + 3 = 0...
 No real solution

.SH See also

   setjmp  saves the context
           \fI(function macro)\fP
   longjmp jumps to specified location
           \fI(function)\fP
   C documentation for
   jmp_buf
